Conventionally, a fuel cell stack composed by stacking a plurality of so-called single cells which hold a membrane electrode assembly (hereinafter abbreviated as MEA) provided face to face with an anode electrode and cathode electrode interlaying a solid polymer electrolytic membrane by pinching/holding with separators made of metal or carbon with good conductivity is known. In a fuel cell in which the fuel cell stack is built in, a fuel cell gas supplied to the anode electrode is ionized on a catalyst electrode and moves to the cathode electrode through a moderately humidified solid polymer electrolytic membrane. Electrons generated during then are taken out into an external circuit and utilized as a direct current. To continuously taking out such an electrical energy, it is necessary for each cell to function favorably.
A voltage between separators composing each cell is measured in operations of the fuel cell to know whether or not the each cell is in a normal condition. For example, in a fuel cell described in pages 3 to 5 and FIGS. 8 and 9 in Japan patent laid open publication 11-339828, the voltage is measured, as shown in FIGS. 1A and 1B, by inserting a connector 127 like a socket into a terminal 119 formed in a separator 111. Meanwhile, the terminal 119 of the fuel cell is connected with a processing circuit which processes a cell voltage. To be more precisely, the terminal 119 is connected with the connector 127, it is connected with the processing circuit via a harness 125 consisting of lead wires, and a number of the harnesses 125 corresponding to those of the terminals 119 are connected.
Meantime, the more the number of separators becomes in a conventional voltage measurement, the more that of connectors to be inserted to each terminal, so there exists a problem that a workability of attaching work of these connectors becomes worse. For the problem, although unifying a plurality of connectors is thought of to simplify the attaching work of these connectors, there exists another problem that a workability of attaching work of these connectors becomes worse in case of unifying a plurality of connectors due to a total weight increase of the module. Moreover for the problem, although dividing the unified module into several modules and attaching them to one piece made of each cluster of terminals is thought of, it is necessary to broaden a distance between separators considering thickness of neighboring modules, thereby causing still another problem that a size of a fuel cell totally becomes larger.
Moreover, in the fuel cell with a module or modules described above, if separators are displaced along their stacked direction due to such as a separator thermal expansion deriving from an impact, vibration, and/or rapid temperature change, positions of modules attached as an outer covering and those of separators are relatively misaligned. Such the position misalignment causes breakages of terminals and/or connectors and poor connections of terminals with connectors. Accordingly, connector positions need to be adjusted corresponding to the misalignment.
Furthermore, between the connectors connected with the terminals and circuit boards consisting of the processing circuit, a harness consisting of lead wires and the like connects, and a number of harnesses corresponding to that of cells or terminals are provided, thereby there existing a problem that a connected structure by the harnesses in itself is low in its reliability. In addition, many lead wires are provided as the harnesses between the connectors and circuit boards, so there exists another problem that handling is not easy.